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Addendum to Urban Land-Use Study Plan: well core samplesTo: wgwilber@usgs.gov,jszogors@usgs.gov,afardis@usgs.gov,naguirre@usgs.gov,wlapham@usgs.gov,cprice@usgs.gov, jbarbash@usgs.gov,capel@usgs.gov From: CN=Paul J Squillace/OU=WRD/OU=USGS/O=DOI PostedDate: 03/19/2003 06:54:38 AM There has been a change in the collection of organic carbon and sediment size analysis for the Urban Land Use Studies. Prior guidance (OFR96-217) asked for organic carbon and size analysis in 2 major lithologic units within the unsaturated zone and at the screen interval. Soil organic carbon was to be recorded from the NRC county survey information. New guidance asks for organic carbon and size analysis from the top 6 inches of soil (after removal of grass and thatch on top of the soil), the screen interval, and one major lithologic unit in the unsaturated zone. The order of priority is soil, screen interval, major lithologic unit in the unsaturated zone.
(1) Soil organic carbon was dropped from the revised (shorter) field sheet form to reduce the work load on study units doing land-use studies. (2) NRC organic carbon is calculated from loss on ignition (LOI) and may not be directly comparable to NWQL method 2503, especially in when the organic carbon content is very low. NRC does treat samples they suspect have large inorganic carbon content before LOI. All organic carbon analysis for NRC is done in Lincoln NE (Tom Reinsch (402) 437-4179). (3) Lee Norfleet (334) 844-4741 ext 176 (Soil Scientist, organic carbon specialist, Auburn Alabama) suggested analysis of the top 6 inches of soil if only one sample was going to be collected in the soil horizon. He thought this sample would give us the most information for the whole soil horizon.
Paul Squillace (pjsquill@usgs.gov) (605) 355-4560 ext 239 |